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VERTICAL SEISMIC PROFILING IN COAL *
Author(s) -
GREENHALGH S. A.,
SUPRAJITNO M.
Publication year - 1985
Publication title -
geophysical prospecting
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.735
H-Index - 79
eISSN - 1365-2478
pISSN - 0016-8025
DOI - 10.1111/j.1365-2478.1985.tb00773.x
Subject(s) - seismogram , geology , vertical seismic profile , attenuation , coal measures , seismology , mineralogy , coal , coal mining , synthetic seismogram , seismic wave , structural basin , paleontology , optics , physics , engineering , waste management
A bstract The intellection of seismic wave propagation in coal measures demands direct observation of the wavefield progression. Two vertical seismic profiles with high spatial and temporal sampling, were recently recorded in the Sydney Basin coalfields as part of an experimental coal seismic program. Static corrections and interval velocities were obtained by an automated system to determine first kicks and pulse rise times. Upgoing and downgoing waves were separated in the f —k‐plane using a novel technique of contour slice filtering. The isolated upgoing waves clearly display reflections from the major coal seams within the stratigraphic sequence. The downgoing wave spectra were subjected to attenuation analysis. The deduced specific quality factor Q for Permian coal measure rocks lies in the range 20–70. Similar estimates were obtained in the time domain from measurements of pulse broadening. Synthetic VSP seismograms, computed using an exact recursive formulation, are an indispensable aid to interpretation. They illustrate the filtering effects of coal seams and sequences, and the effects of the contribution of internal and free‐surface multiple reflections in the recorded wavetrains.